As disclosed in the following patent literature 1, there is a carburetor comprising a rotation-typed control valve, in which the second bleed air passage is opened or closed according to an opening degree of the throttle valve by a lower end portion forming with a grooving portion on a part of an outer periphery of a valve stem, thereby simplifying the structure of the control valve, and opening or closing the second bleed air passage accurately according to an opening degree of the throttle valve.